Presently, water-based inks used for printing onto polyboard substrates primarily used for milk and juice cartons and other paper/board substrates are based on epoxy esters which contain Bisphenol A (BPA) and polymers comprising BPA. However, due to suspected toxicity, regulations are changing such that these inks can no longer contain Bisphenol A and polymers comprising BPA.
Consequently, there is a requirement to provide water-based inks for general printing, and in particular, for flexographic and gravure printing for polyboard substrates, that exhibit acceptable performance and do not contain Bisphenol A (BPA) and polymers comprising BPA.
WO 0073392 discloses the use of hybrid alkyd acrylic resins in inks for use on polythene coated board used for milk cartons.
US2009/0297796 discloses water based screen printing inks that may be suitable for other printing methods, primarily containing specialist pigments and a cross linker.
U.S. Pat. No. 7,807,739 discloses an aqueous composition for coating substrates comprising a cross linkable polymer, an acrylic polymer and an epoxysilane.
US2013/0309516 is directed to a coating composition having an acrylic polymer with a low glass transition temperature that contains a cross linkable functional group and a cross linking agent.
JP3301267 is directed to water color inks containing a resin for use on corrugated fiberboard.
Finally, CN101812255 is directed to an ink containing an acrylic resin for use on a high temperature resistance carton.